1. Field of the Invention
The present invention relates to the field of telemetering used in collecting of sales information of an automatic vending machine and the like or the field of telematics used in delivering traffic information.
2. Description of the Related Art
In recent years, telemetering or telematics used in collecting or delivering information through a radio packet communication network has been in widespread use. Originally, telemetering was a general term given to the mechanism to read a measured value of a measuring instrument by using a communication circuit. However, in recent years, the term is generally used not only for reading data, but also for monitoring of operation or remote control of a device. Examples of “telemetering” include a sales management system for an automatic vending machine, a consumption management system of gas, water, or the like, and a management system in unmanned parking lot, and the like. As an example of the sales management system of automatic vending machine, refer to Japanese Patent Publication 2003-51056. The term “telematics” means real time provision of information service by combining a communication system with mobile objects such as a vehicle. Examples of “telematics” include an on-vehicle information system for providing in real time traffic information or navigation information to a terminal mounted in a vehicle.
In such field, a communication device for connecting to the radio packet communication and high-level equipment using the communication device are required in a remote area. The high-level equipment corresponds to DTE (Data Terminal Equipment), and the communication device corresponds to DCE (Data Circuit-terminating Device). For example, in a sales management system for an automatic vending machine, the control equipment performing sales control and temperature control in the machine corresponds to the high-level equipment.
The radio packet communication network is constructed by using a network connection service for connecting a LAN and a radio communication terminal provided by carriers (communication common carriers). In this network connection service, a network router is provided in the LAN of a user of the service, and through a radio packet communication network constructed by the service, a radio communication terminal can be connected to the LAN. The radio communication terminal is usually connected to the LAN by using PPP (Point-to-Point Protocol) through the radio packet communication network only when necessary. Here, an address space of the radio packet communication is defined in advance by the carriers. An IP address of the radio packet communication network side (WAN side) is allotted with a fixed IP address included in the address space. With respect to the IP address of the radio communication terminal, a fixed IP address included in the address space is allotted or one piece of the IP addresses included in the address space is dynamically allotted when connected with the radio packet communication network.
Now, the standard, service configuration and the like of radio packet communication networks vary according to carriers, and thus, the standard and operation of the communication device also vary according to the carriers. For example, depending on the network connection services provided by the carriers, an allotment method, connection method, authentication method and the like of the IP address given to a connection terminal vary. Consequently, to design high-level equipment, carriers and communication device to be used are selected in advance, and an operation corresponding to the communication device is performed.
In recent years, there have been requests to change the carrier after having constructed such system. The reasons for this include, for example, “the condition of radio wave provided by the carrier in the location of placement of the high-level equipment is unstable or inappropriate”. Particularly, there have been requests to change from the network connection service allotting a fixed IP address to a connection terminal to the network connection service dynamically giving an IP address.
However, there has been a problem that the network connection service dynamically giving an IP address destabilizes the IP address of the connection terminal and this prevents the LAN side device from starting a communication with the connection terminal. In addition, the change of the carrier or the service necessitates the change of the communication device, and consequently the high-level equipment must be also changed and modified accordingly. The high-level equipment is placed, due to the properties of such system, in remote areas in a dispersed manner, and when the high-level equipment is already in the market, it takes a vast amount of works for the change and modification of the high-level equipment. Not only the change of the carrier, but also the change of model of the communication device may cause the same problem even if the same carrier is used. This problem may take place also when a change of the carrier or a model change is made in the future. Hence, to construct a system, it is essential to cautiously select a service, a carrier, and a model. Moreover, when a system using a plurality of carriers, services, and communication device is constructed, high-level equipment compatible with carrier or communication service must be prepared. This creates a problem that a costly system is constructed.